1. Technical Field
Embodiments disclosed herein relate to an apparatus for and method of handling a reticle in a lithography system, such as an extreme ultraviolet lithography (“EUVL”) system.
2. Related Art
The need for protection from particulate matter (i.e., dust, dirt, etc.) contaminating objects of interest is required in many fields of application, including applications in semiconductor manufacturing such as microlithography. As microprocessors become faster and more powerful, an ever increasing number of transistors are required to be positioned on a semiconductor chip. The increased transistor density necessitates closer placement of the transistors, smaller device sizes, and interconnects that take less space. An ever increasing accuracy and precision in the methods for laying down the circuits on the chip is therefore required.
To achieve such great circuit density, the exposure radiation wavelengths used in microlithography are decreasing from visible to VUV, EUV, and smaller in next generation lithography (“NGL”) tools. A reticle with a desired pattern on one side is illuminated by the radiation, and the radiation transfers an image of the pattern to the substrate to create a part of the desired circuit.
Conventional reticles are typically for use with longer wavelength exposure radiation. As a result, a clear faceplate, called a pellicle, can be utilized to cover and protect the pattern side of a reticle. As the features grow smaller, resulting in the need for shorter wavelengths, e.g. EUV radiation, the pellicle can not be utilized as present materials absorb too much of the radiation for process efficiency and deteriorate quickly. Moreover, the distortion of a reticle has a greater impact on process yields with shorter wavelength radiation, making the flatness of the reticle critical. Therefore, protecting both the pattern side and the side of the reticle used to mount it in a lithography system from contamination (and thus physical distortion) becomes important. Therefore, there is a need to provide reticles and an apparatus for handling reticles to minimize contamination and warping. This need exists throughout the reticle lifetime following final cleaning and inspection.